Detonation risk?

[CMF_Red Menace]

All,
I'm going to swap 1.0 pistons into a 1.3 (or more accurately, stroke a 1.0 to 1.3 using a 1.3 crank and rods). However, I would like to keep the stock 1.3 cams and fuelling which will give me very high dynamic compression. Has anyone got experience of this set-up (I'm looking at you, Frank) and should I expect detonation on 95 octane fuel?

I don't want to fit wild cams just yet if I can help it because this is likely to require complementary fuelling changes (and reduce low-end torque), so I'll fit water injection if I have to, but I don't fancy the complexity of controlling it all if it isn't necessary.

Any advice gratefully received.

 

[CMF_frank2]

Red Menace WROTE:

(I'm looking at you, Frank).

lol, no it,ll be fine on unleaded red menace, CG,s seem to be very det resistant, i,ve got 2 spare 1.3crank/1.0piston engines and they ran fine with various cam combinations and ignition timing settings

frank

 

[mik]

whats the power gain of doing this? just about how much is it then?
got a spare 1.0 engine at home, never thought of doing that.

cheers mik

 

[CMF_frank2]

mik WROTE:

"whats the power gain of doing this? just about how much is it then?

got a spare 1.0 engine at home, never thought of doing that.

cheers mik

its useful if you,re fitting cams mik, (it restores the compression that the extra duration loses eh)
and makes good use of my (higher octane) lpg.
the gudgeon (wrist) pins are an interference fit tho (ie MEGGA tight )

frank

 

[CMF_Red Menace]

Good news I'll crack on with it then! I'm going to get a local engine shop to press the wrist pins out, they want £20 to do the whole job and it'll save me getting stressed and leathering things with big hammers and blocks of wood and probably breaking something. Haynes tells me that I can't re-use the pistons after they've been pressed out, but I'm going to disregard that small point on the basis that Frank's already done it.

Thanks for the advice. Don't watch this space - it's likely to be full of stress and failed engine components, but if by some miracle I come up with the goods at the end of it I'll post something

 

[CMF_frank2]

yeh, i think you can easily damage a piston if you press against the piston itself, my tool has a fork inside that only presses against the conrod tho (which is where the interference fit is eh) and to re-assemble, the pins slide in a treat if you heat the rod up, but you only have about 0.5 secs to set them central tho
just dont mix the crankshells up tho eh (they are sized/graded individually)

 

[CMF_Red Menace]

That's valuable information. I'll talk to the shop to see what they're planning. Thankyou.

Minor mission this afternoon - picked up the 1.0 engine from the local yard. As a bonus, he let me have the gearbox with it even though I only paid for the engine - they hadn't separated the two. Forklifting the engine into the car was easy enough, but owing to the weight of the gearbox, not surprisingly, I didn't stand much chance of lifting it all out again. Took everything I needed to remove off the engine, then split the engine and box in the Micra's boot! Still a massive weight when I shifted it from the car to the garage though. A friend's lending me a hoist to do the swap with, but I don't have it yet.

I'm going to have to try to mix and match the main bearing shells to get the old crank into the new block. I'll definitely note which one started where though, but I might need a few new ones if I'm unlucky.

 

[CMF_frank2]

sounds like fun
personally, i always lower the g/box to the floor (shafts etc in situ) then hump the engine over the crossmember

frank

 

[CMF_Red Menace]

Out of interest, how thick were you able to make the fork on your tool? I've figured a design that I can bodge together from plate; the only restriction on the plate thickness is the space I've got at the business end.

As for getting the pins back in, are you heating them in an oven or with a torch?

Driveshafts in situ - that's good news. There's adequate sideways movement to get the engine off the input shaft then, provided the driver's side engine mount is taken off first.

Thankyou for all the advice. You've saved me a lot of hassle and broken bits.

(today, everything aches!)

 

[CMF_frank2]

Red Menace WROTE:

"Out of interest, how thick were you able to make the fork on your tool? I've figured a design that I can bodge together from plate; the only restriction on the plate thickness is the space I've got at the business end.

it was an old balljoint splitter mate, i,ve got a better pic somewhere (cant find the damn thing !)

 

[CMF_frank2]

Red Menace WROTE:

As for getting the pins back in, are you heating them in an oven or with a torch?

Driveshafts in situ - that's good news. There's adequate sideways movement to get the engine off the input shaft then, provided the driver's side engine mount is taken off first.

and i used a little butane torch, if you polish the rod first, it will turn blue when its hot enough (or else put some spit 1/2 way down the rod lol)
and the g/box pulls off and lowers down ok, leaving plenty of room to lift the engine out

 

[CMF_Red Menace]

Am now armed with mild steel plate and am going to produce a similar tool. Can I ask whether you're able to drive the pin out with a hammer and wooden block, or whether you're using a press?

 

[CMF_frank2]

Red Menace WROTE:

"Am now armed with mild steel plate and am going to produce a similar tool. Can I ask whether you're able to drive the pin out with a hammer and wooden block, or whether you're using a press?

just a hammer and drift (a flypress would be better tho eh), i tried using heat but you cant heat the rod without the piston and pin soaking the heat too
the pistons and rings changed shape in 2000 btw (slipper type piston, and skinny rings)

frank

 

[CMF_Red Menace]

One suitable tool (I hope). Welds are impossibly ugly, but I think it will work. I'll have to carve the forks to size once I have a piston out to check them against.

 

[CMF_frank2]

looks good mate
talking of bird**** welds, here,s another pic of mine

frank

 

[CMF_Red Menace]

Pants, just realised that the pistons won't fit through the bottom end. I was hoping to get away without disturbing the head; not gonna happen.

[edit] Double pants, I did what you're not meant to and used a chisel to separate the timing cover from the block. Not only did I peel a sliver of aluminium off the block, I managed to do it adjacent to the O-ring which seals the oil pump output. Time for some chemical metal to patch that up, I think - don't fancy finishing the rebuild only to find that it does not, in fact, seal any more.

[edit again, later] Got the new engine apart; head off, crank and rods out. Some minor rust spots in number 4 cylinder; I've passed a long Stanley knife blade round the bore to remove the rust and then Scotchbrited the rest to blend it back in. Guess we'll see how well it holds compression thereafter but I'm happy to have got this far. I think I'll rebuild it as far as the short block stage in the garage, then fit the head once I've got the block into the car. That way, I stand a chance of running the wiring correctly and not missing any of the hoses.

 

[CMF_l3hur4y]

Dont get why u want 1.3 cams..... the top end off all k11 engines are the same.... only thing that changes is the stroke.... so why would u wanna put 1.0 pistons init...... an the pistons are also have a bigger diamiter so they wouldn fit..... im confussed

 

[CMF_Red Menace]

It would be better to say that the top ends are interchangeable. The 1.3 cams have higher lift and longer duration, but will drop straight in (you'll have to play around with shims to get the right clearance between cam lobes and tappets though).

Don't believe everything you read, either - the bore of the 1.0 and the 1.3 is identical at 71mm, so the pistons are a direct swap. As for why it's worth doing:

Both engines compress the mixture in the cylinder by the same ratio (9.5:1). The 1.3 takes in a larger charge to start with (1275cc / 4 = 318.75, compared to 1000cc / 4 = 250cc for the 1.0), so the compressed volume you're left with afterwards must also be larger.

Because the heads are identical, as you righly point out, this larger volume is achieved by changing the shape of the top of the piston. The top of a 1.3 piston is slightly bowl shaped to give a little extra volume to accommodate the larger volume of compressed charge. 1.0 pistons are flat-topped.

If you swap the flat-topped pistons from a 1.0 into a 1.3, the compression ratio goes right up from 9.5:1 to about 12:1. This gives a little more torque and power. It's also useful if you've got aggressive cams, as these tend to lower cylinder pressures at low engine speeds and would otherwise give you an engine with no low-end torque (not easy to launch).

Hope that helps.

 

[CMF_Red Menace]

Yeesh Frank, you weren't wrong about them being a tight fit. My tool is bending (at least the welds hold!) but still the gudgeon pin doesn't move. That tool is made from 8mm thick stock! Clearly the overhang is too much

[edit] Trimming it to remove the overhang. Then we'll see if the welds are up to it for a second round.

[edit again, later] Reshaped the tool. Leathered the gudgeon pin with a 20kg chunk of steel. The pin has moved not a millimetre. The tool has bent beyond salvage. These pins are ridiculously tight. I have no way to remove them.

I've spoken to a local engineering shop. They can press the gudgeon pins out but would expect to scrap a couple of pistons in the process. If they pressed the 1.3 pistons off the con rods, and I cut the 1.0 con rods off the pistons, then I would have one set of rods, pins and pistons to assemble - and one shot at getting the gudgeon pins in. Mess up once, and I might as well scrap the lot. Not a pleasant prospect.

 

[CMF_frank2]

yes they do be tight RM, but they fall in by gravity when you heat the rod tho
i rigged up a rod that slid into the gudgeon pin and had a collar that hit against the piston when the pin was inserted the right amount (ie, you shove it in till it stops dead)

frank

 

[CMF_Red Menace]

Yeah, from looking at where the pins sit, with one face of the little end of the rod hard up against one side of the piston, the end of the pin is flush with the outside face - almost as if it was designed to allow that. I was planning to make just such a rod.

You mentioned that you'd run all sorts of cams and ignition timing with the high CR. Can I ask whether you had to retard the ignition at all to get the standard cams to work? I'm a little concerned that, if I get problems, I won't have any 1.3 pistons to fall back to.

 

[CMF_frank2]

i,ve usually got a fair bit of cam advance to lower the powerband (probably largely chain stretch)
and my ignition curve seems to be compromised by the extra advance of the 1.0 ecu (apparently they have 6 or 8 deg extra full advance)
so if i advance it the engine sounds very harsh at high revs (not actually pinking, just very coarse), but if i retard it the engine lacks response and hesitates but runs smoother top-end
i,m trying out an autosprint 260deg/10mm lift inlet cam atm, (and the piper exh) and the 0 to 60 is getting ever closer to 7 sec at last

 

[CMF_Red Menace]

7s would do nicely but I'll settle for a runner first. I'm guessing the powerband isn't wide enough to eliminate the second gearshift from your 0-60? It seems to happen about 55mph...

Time to break out the grinder (again) and cut some con-rods off.

[edit] No access to get the grinder in; the piston skirt is too deep. Furthermore, while I diligently protected the outside of the piston rings while trying to drill through the con-rod, I didn't realise until too late that the lowest of the three rings is in a groove that breaks right through into the inside of the piston. It's now completely full of swarf, and still I'm nowhere near getting the gudgeon pin out. I don't particularly want to lay out a couple of hundred quid for new rings.

[edit again, 2:30pm] I have a piston. Woohoo! The inside is full of swarf, the lower ring likewise, and I've consumed more cutting bits than I would have believed possible, but for all that, I have one. Of four. Hmm.

[edit again, 4pm] Two pistons. Marching on...

[9pm] Three pistons down, one to go. The local shop say they can heat and fit the pistons to the rods, so I think I can now see a clear path from here to the end of the job. That's a first.

 

[CMF_Red Menace]

1pm, Thurs: Four pistons out. However, in a moment of eye-popping stupidity, I drove the drift into the gudgeon pin bore in the piston and converted the close clearance into a fit. It was only over about the first third of the bore, so I've dressed it out, polished it smooth and persuaded the gudgeon pin that it will now rotate smoothly without undue friction or binding. However, there is now (inevitably) a little play in the journal at that point. Given that most of the fit is intact, I think it should be OK when the pin is through both piston journals and the rod. I can't check, even without the rod, as the gudgeon pin has some minor marks on it which might scratch the surface further.

I'm getting good at snatching defeat from the jaws of victory here. On the plus side, at least I should get to work out exactly which mistake is the most serious - I'll let everyone know when it blows up and I do the teardown

 

[CMF_frank2]

lol red menace, every cloud...yada yada
the fun is in the making imo (i just knocked up a perspex r/screen for instance)

frank

 

[CMF_Red Menace]

Verrry nice. From the pic, it looks curved - did you blow it, suck it down over an existing screen, use some other method, or are my eyes deceiving me and it's actually flat?

 

[CMF_frank2]

Red Menace WROTE:

"Verrry nice. From the pic, it looks curved - did you blow it, suck it down over an existing screen, use some other method, or are my eyes deceiving me and it's actually flat?

no its flat RM, to save jackin your thread, there are some more pics at the bottom of this page
http://www.micra.org.uk/showthread.php?t=22225&page=14

frank

 

[CMF_Red Menace]

I should mention - I've now got a good few spare 1.0 bits, so if you need:
- Crank
- Flywheel / clutch, with 50k on
- Big end shells
Then you're more than welcome, they're not much use to me except as ornaments, and they'll only get scrapped otherwise. I can post the shells if they're useful? I imagine they're probably the only things on the above list that would really be of much use, but figured I'd mention it regardless.

 

[CMF_lurch]

Mate is the flywheel pre98 if so i'll take it off your hand if you don't want it

 

[CMF_frank2]

Red Menace WROTE:

"I should mention - I've now got a good few spare 1.0 bits, so if you need:

- Crank

- Flywheel / clutch, with 50k on

- Big end shells

Then you're more than welcome, they're not much use to me except as ornaments, and they'll only get scrapped otherwise. I can post the shells if they're useful? I imagine they're probably the only things on the above list that would really be of much use, but figured I'd mention it regardless.

thanks for the offer RM, but i,m ok for parts tho atm cheers

frank

 

[CMF_Red Menace]

Lurch, it's R-registered (1997?) and is for the lightweight box that went with early CG10s. You're more than welcome to it, though as you're aware it's heavy and you're in Ireland... I don't want anything for it except the postage, though you're welcome to pick it up (Derby, UK) if you're over this way.

 

[CMF_lurch]

Well i live in the u.k now so if you could send me your address via a p'm i'll collect it off you tomorrow